Structure, method, and device for splicing laminated films

ABSTRACT

A coupled portion of mutual laminate films sufficiently contributes to the formation of a packaging bag in that the coupled portion itself has excellent airtightness and liquid tightness. The tensile strength required for the laminate film is given to the coupled portion, whereby a temporary stop of a packaging apparatus is useless when a connecting portion of the laminate film is passed through the apparatus, thereby enhancing the operation efficiency and improving the yield of the material. Oriented base film layers are joined in a miter form at the coupled portion between a rear end portion and a front end portion of laminate films comprising oriented base film layers and sealant layers.

TECHNICAL FIELD

This invention relates to a coupling structure, a coupling process and acoupling apparatus of coupling a rear end portion of one laminate filmwith a front end portion of another laminate film without using anadhesion tape or the other coupling material in laminate films,frequently a laminate film used for packaging, in which a mutuallycoupled portion of the laminate films is also subjected to liquid-tightor airtight heat sealing likewise the other portion in the bag formationor the like through heat sealing.

BACKGROUND ART

For instance, a laminate film for packaging used for the production of apackage bag filled with a material to be packed, which is used in a caseof continuously filling and packaging a liquid body, a powdery body orother or a case of discontinuously filling and packaging it, isgenerally applied to a packaging apparatus at a state of roll-shapedwinding through a printing step, a laminating step and a slitter step.

In this case, the slitter step is mainly carried out for cutting andremoving side portions of a laminate film to render a width size of thefilm into a constant value, and adjusting a length of the laminate filmwound in roll shape and coupling the laminate films so as to render atotal winding length of the laminate film into a given length such as1000 m, 2000 m or the like, and connecting the laminate films to eachother after the cut removal of poor printed portion, poor laminatedportion and the like. For this end, 2-3 film coupled portions arefrequently existent in the wound laminate film of 2000 m.

Heretofore, the coupling of the laminate films each comprising a basefilm layer and a sealant layer is carried out by butting a rear end ofone laminate film to a front end of another laminate film through anadhesion tape or the like attached to a side of a base film face andjoining them.

In the thus coupled laminate film, however, when the laminate film issubjected to longitudinal sealing and lateral sealing at a two foldedstate in a widthwise direction to form a packaging bag under a fusion ofthe sealant layer, the adhesion tape or the like made of a materialdifferent from the laminate film brings about the increase of thethickness of the laminate film, and also a sufficient heat transmissionfrom a heat sealing blade to the sealant layer is obstructed by theproperties inherent to the adhesion tape or the like and hence it issubstantially impossible to rapidly melt the sealant layer to an extentenough to the fusing between the mutual sealant layers. For this end,when the continuous filling, packaging and the like are carried out, forexample, by applying the laminate film to the packaging apparatus, evenif the film coupled portion existing in the free end portion of thefolded laminate film could be passed between longitudinal heat sealingblades as a pair of rotational sealing blades rotating at a constantclearance as it is, the sealant layer can not be sufficiently heat-fusedeven under a heating and pressurizing action of the longitudinal heatsealing blade due to the presence of the adhesion tape or the like, andhence there is a problem that leakage, scattering and the like of theliquid or other material to be packed is caused.

The similar result is also caused by joining with the adhesion tape orthe like because end portions of both laminate films can be coupled toeach other at a strength required in a packaging bag with a sufficientairtightness or liquid tightness.

Heretofore, the whole of the packaging apparatus or a main part thereofsuch as heat sealing function part, filling function part and the likeis temporarily stopped every the running-out of the coupled portion ofthe laminate film from the wound film and the coupled portion is passedthrough the main part of the apparatus and thereafter the filling andpackaging are restarted. In the restarting, affirmation of amount ofmaterial to be packed in the packaging bag, confirmation of heat sealingposition and sealed state, confirmation of cutting position of thepackaged bag and forming position of tear notch, and so on are conductedto put all of them into acceptable ranges, and thereafter the apparatusis really re-worked.

Therefore, many times and operating numbers are required form atemporary stop of the apparatus or a main function part thereof to are-working of the apparatus, which cause a serious problem in theworking capacity and efficiency, while it is obliged to consume greateramounts of the laminate film and the material to be packed, which causesa problem of lowering the material yield.

For this end, the invention provides a coupling structure, a couplingmethod and a coupling apparatus of a laminate film, in which endportions or side portions of laminate films are coupled to each otherwithout using a coupling material such as an adhesion tape or the likeand the resulting coupled portion is sufficiently contributed to make apackaged bag likewise the other portion of the laminate film and also atensile strength required in the laminate film is given to the coupledportion, whereby the capacity and efficiency of the filling andpackaging work for the material to be packed can effectively be enhancedand the yield of the material can be largely improved.

DISCLOSURE OF THE INVENTION

A coupling structure of a laminate film according to the invention is astructure that laminate films each comprising a thermoplastic orientedbase film layer such as a biaxially oriented nylon film layer, abiaxially oriented polyester film layer, a biaxially orientedpolypropylene film layer, a biaxially oriented ethylene-vinyl alcoholcopolymer film layer or the like and a sealant layer such as variouspolyethylene layers, an ethylene-vinyl acetate copolymer layer, anon-oriented polypropylene, an ethylene-acrylic acid copolymer layer, anionomer layer or the like are mutually coupled at each front end portionand rear end portion to each other, and mutual oriented base film layersare fusion-joined in a mitre form and a protruding amount of the fusionjoint portion from the other film portion is about 50-800 μm.

In the invention, various film layers, or a metal foil such as aluminumfoil or the like, a paper, various vapor deposited layers, a vinylidenechloride copolymer coating layer, or other coating layer may beinterposed between the oriented base film layer and the sealant layer.

The above coupling structure of the laminate film can be realized, forexample, by overlapping both the laminate films so as to oppose theiroriented base film layers to each other and hot-cutting these laminatefilms with an impulse sealer, preferably under a pressure to fusion-joinboth oriented base film layers in a mitre form at their cut edges and aneighborhood thereof.

In this case, a protruding amount of the fusion-joint portion betweenthe mutual oriented base film layers from the other film portion may beabout 50-800 μm.

For example, when the laminate film is applied to a continuous fillingand packaging apparatus for the material to be packed, the joint portionis run out at a filling space side for the material to be packed or at astate of protruding into an inside of a packaging bag to be produced byfolding the film into two in a widthwise direction. When the jointportion of the laminate films existing at their folded free end portionsand extending in the widthwise direction of the film passes between apair of rotating longitudinal seal knifes, sufficient heat fusion amonga folded of the protruding joint portion onto a sealant layer of, forexample, a back-side laminate film, the sealant layer and a sealantlayer of the joint portion opposite thereto is carried out.

Furthermore, another side sealant layer of the joint portion stillexposed by such a heat fusion of the joint portion is sufficientlyheat-fused to a sealant layer of the other free end portion of thelaminate film, so that the resulting longitudinal heat seal portion canensure the airtightness and heat seal strength as is expected.Therefore, the joint portion can sufficiently contribute to liquid-tightand airtight formation of the packaging bag.

They are true even when the joint portion of the oriented base filmlayer overlaps with a lateral heat seal portion of the packaging bag.

Under such a coupling structure of the laminate films according to theinvention, steady operation of the packaging apparatus can be continuedeven when a fastened portion of the film is existent. Even in the thusobtained packaging bag including the fastened portion, the material tobe packed can be adequately packaged, so that there can be sufficientlyremoved fears such as deficiency or impossibility of the heat seal,scattering and leaking of the material to be packed and the like.

Therefore, even when the fastened portion of the film passes through theheat seal knife of the packaging apparatus or the like, it is useless totemporarily stop heat-sealing function part, filling function part andthe like and hence the improvement of operation efficiency, efficiencyand yield of material are realized.

Such an improvement of the material yield becomes more conspicuous whenthe fitting of front and rear patterns at the joint portion is carriedout in case that the laminate films have a printed pattern or the like.

Incidentally, in case of a laminate film consisting of abiaxial-oriented nylon film layer having a thickness of 15 μm as anoriented film layer and a polyethylene layer having a thickness of 50 μmas a sealant layer, when two laminate films are fused by using animpulse sealer, a joining strength between both the nylon film layers isabout 5N per a width of 15 mm, which is a value fairly larger than atension of about 3.5 N per a width of 100 mm acting to the laminate filmin the packaging apparatus in the running-out from a wound roll-shapedfilm, so that the laminate film run-out from the wound film never causean unexpected breakage or the like at the joint portion of the nylonfilm layer.

In the coupled structure of the laminate films as mentioned above, thefusion-joint portion of the oriented base film layer is preferable to bearranged so as to extend obliquely with respect to the widthwisedirection of the laminate film.

This can shift the extending position of the fusion-joint portion to theextending direction of the longitudinal heat seal portion between afront portion and a rear portion of a packing bag when the laminate filmis folded into two in the widthwise direction and the free end portionsoverlapped with each other are subjected to longitudinal heat sealingand to lateral heat sealing at intervals in a longitudinal direction ofthe film fill and package the material to be packed, whereby stressconcentration or the like can be advantageously prevented to enhance thestrength of the packaging bag as compared with a case that the jointportions are positioned between both portions to overlap with eachother.

Preferably, the mitre-shaped fusion-joint portion of the oriented basefilm layer is folded toward the one laminate film side, and thenmutually opposite sealant layers, i.e. the sealant layer of themitre-shaped joint portion and the sealant layer of the one laminatefilm are previously joined to each other.

This joining can be carried out by heat-fusing both the sealant layersthrough heat sealing.

According to such a coupling structure, the joint strength between boththe films can be enhanced to about 35 N per width of 15 mm under thesame lamination structure as mentioned above, so that even if anunexpected dynamic load is applied to the fastened portion of the film,the breakage of the film or the like can be sufficiently prevented atsuch a fastened portion.

The coupling apparatus of the laminate film according to the inventionis an apparatus of coupling end portions or side portions of laminatefilms each comprising a thermoplastic oriented base film layer and asealant layer, which comprises a pair of bases positioned at an intervalpermitting an insertion of each end portion of side portion of thelaminate film, at least one pusher arranged on the one base between bothopposite bases so as to push the end portion or side portion of thelaminate film toward the side of the other base, and upper and lowersealers arranged on the other base at a position corresponding to thepusher.

In this apparatus, the each end portion of, for example, the laminatefilm is inserted between the pair of the bases at a posture of facingthe oriented base film layers to each other, while the oriented basefilm layers are fused and joined to each other in a mitre form by thelower sealer under a press through the pusher, and then the mutuallyopposite sealant layers are fused to each other by the upper sealerunder a press through the pusher at a posture of folding the jointportion between the mutual oriented base film layers toward the side ofthe one laminate film, whereby the rear end of one laminate film and thefront end of the other laminate film can be coupled to each other with ahigh airtightness and liquid tightness without using a coupling materialsuch as an adhesion tape or the like. Also, the coupled portion iscontributed to the formation of a packaging bag under an action of theexposed sealant layer likewise the other portion of the laminate filmand a tensile strength required in the laminate film can be given to thecoupled portion. For this end, even when the coupled portions are runout from the wound film in the filling and packaging of the material tobe packed, the steady operation of the packaging apparatus can becontinued to continuously produce a packaging bag filled with thematerial to be packed.

Moreover, the folded posture of the joint portion between the mutualoriented base film layers toward the side of the one laminate film canbe surely realized by forming the mitre-shaped joint portion and pullingup the other laminate film toward the upper side at a given baseinterval such as 1-5 mm, preferably 2-3 mm to delay the pulling of thejoint portion based on friction between the mitre-shaped joint portionand the base. Also, the fusion between mutual sealant layerscorresponding to each other through such a folding can be carried out byfunctioning the upper side sealer under an action of sufficient pushingforce through the pusher, whereby the occurrence of protrusion resultedfrom the folding fusion can be sufficiently prevented.

Therefore, the efficiency of the filling and packaging operation and theefficiency and the yield of the material can be largely improved ascompared with the conventional technique requiring the temporary stop ofthe main function parts or the like in the packaging apparatus every therunning-out of the coupled portion of the laminate film.

In such an apparatus, it is preferable that the sealer arranged downsideis a cutting sealer and the sealer arranged upside is a fusion sealer.

According to this arrangement, when all of the laminate films are madeof a thermoplastic resin material, the fusion joining between theoriented base film layers is carried out by the cutting sealer, wherebythe length of the mitre-shaped joint portion of the oriented base filmlayer can be made to a required and minimum one, so that when thesealant layers are fused to each other at the folded posture, the widthof the fused portion can be made to about a line and hence the influenceof the fused portion upon the formation of the packaging bag can be mademinimum s far as possible.

In the insertion of the end portions of the laminate films between boththe bases, when both end portions of these films are preciselypositioned in correspondence to the lower sealer, the length of themitre-shaped joint portion can be sufficiently shortened withoutrendering the lower sealer into the cutting sealer.

It is preferable to arrange an elastic tube or a cylinder conducting atleast forward displacement, preferably both forward and backwarddisplacements of the pusher.

In this case, the forward running of the pusher and hence the pushing ofthe end portion of the laminate film toward the other base side can berealized by expansion of the tube based on the supply of a pressurizedfluid to the elastic tube or forward displacement of a piston rod basedon the pressurized fluid to the cylinder. In the former case, thestructure is made simple and the equipment cost and running cost aredecreased and the maintenance control can be facilitated as comparedwith the case of using a reciprocal driving means such as cylinder orthe like.

Moreover, when the backward displacement of the pusher is carried outaccompanied with the shrinkage deformation of the elastic tube or thebackward movement of the piston rod by joining and coupling the pusherto the elastic tube or the piston rod, the insertion of the laminatefilm between both the bases can be conducted smoothly and easily.

Also, the construction of the apparatus can be made simple by combiningthe pusher with the upper and lower sealers.

On the other hand, when the pusher is arranged so as to correspond eachof the upper and lower sealers, the lower side pusher is functioned tothe fusion joining of the oriented base film layer, while the upper sidepusher can be successively functioned to the folding fusion of thefusion joined portion thereof. For example, when the lower side sealeris a cutting sealer, the oriented base film layers are fusion-joinedunder an action of the pusher corresponding thereto, and thereafter thefusion joined portion is pulled up to the upper side fusion sealerwithout displacing the pusher backward, whereby an extra length can besurely removed from the fusion joined portion.

Moreover, in order to locate the joint portion after the fusion joiningof the oriented base film layers at a position corresponding to theupper side sealer, it is preferable to pull up either one of thelaminate films up to a height restrained by a positioning gauge at astate that the positioning gauge is inserted between the pair of basesand between the respective laminate films.

In this apparatus, a positioning means for the laminate film is arrangedon an upper face side of each of the bases and a length of the endportion of the respective laminate film to be inserted between the basesis specified by such a positioning means, whereby the matching of thelaminate films having a printed pattern or the like at the coupledportion can be conducted simply and easily.

Further, a cutting means of the laminate film such as a shear part canbe arranged at a position beneath the pusher and the sealer in such acoupling apparatus.

This apparatus is effective to not only a case that the all laminatefilms are comprised of thermoplastic resin layers but also the use ofthe laminate film having a non-thermoplastic resin layer of an aluminumfoil, a paper or the like as a middle layer. After the mitre-shapedfusion joining between the mutual oriented base film layers, both thelaminate films are cut below the joint portion to remove the middlelayer or the like, whereby an extra portion followed to the jointportion can be surely removed, so that a fusion width of the jointportion through subsequent folding fusion is made constant and theinfluence of such a folding fused portion upon the packaging operationcan be made sufficiently small.

Moreover, the lower sealer can be rendered into either of the cuttingsealer and the fusion sealer. In the latter case, the accidentalexposure of the middle layer can be surely prevented to more beautifullyfinish the coupled portion.

Although the above is explained with respect to the case that the rearend portion and the front end portion of the two laminate films arecoupled to each other, this is also true in the case of coupling a sideportion of the one laminate film and a side portion of the otherlaminate film to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged section view illustrating a coupled structure offilms according to the invention.

FIGS. 2( a) and 2(b) are section views ideas illustrating a fusion stepof an oriented film layer.

FIGS. 3( a) and 3(b) are schematic views illustrating an example ofslantly existing a joint portion.

FIG. 4 is an enlarged section view illustrating another coupledstructure.

FIG. 5 is a section view illustrating a fusion cutting step.

FIGS. 6( a) and 6(b) are schematic views illustrating a method ofcoupling films in an example.

FIG. 7 is a sectional perspective view illustrating an apparatusaccording to the invention.

FIGS. 8( a) and 8(b) are section views illustrating an embodiment ofarranging a cutting sealer.

FIGS. 9( a), 9(b) and 9(c) are section views illustrating a step ofcoupling laminate films to each other.

FIGS. 10( a), 10(b) and 10(c) are section views illustrating anotherstep of coupling laminate films to each other.

FIG. 11 is a diagrammatically enlarged section view of a coupledportion.

FIG. 12 is an enlarged section view illustrating actual coupled portionof the laminate films at 100 magnifications.

FIGS. 13( a) and 13(b) are enlarged section views of mutual coupledportions having each uneven state in its surface.

FIG. 14 is an enlarged section view illustrating another example of thepusher mechanism.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is an enlarged section view illustrating a coupled portion offilms according to the invention, wherein numerals 1, 2 are laminatefilms for packaging.

Each of these laminate films 1, 2 comprises an oriented base film layer3, 4 made of a thermoplastic resin material and a sealant layer 5, 6directly laminated on the oriented base film layer 3, 4. In this case, amitre-shaped joining between the oriented base film layers 3, 4 iscarried out by coupling a rear end portion of the one laminate film 1with a front end portion of the other laminate film 2.

Such a joining between both the base film layers 3, 4 may be conductedby interposing an adhesive between both the layers, but it is preferablethat in order to conduct the joining at a sufficient strength withoutusing a special coupling or joining material, the fusion of the basefilm layers is conducted while restraining heat shrinkage of both thelayers by violently heating the base film layers 3, 4.

For this end, when both the laminate films 1, 2 are fusion-cut at astate of overlapping the oriented base film layers 3, 4 in opposition toeach other, it is preferable to heat-fuse both the base film layers 3, 4to each other at a cut edge and a neighborhood thereof.

FIG. 2 is a section view ideally illustrating such a fusion step in caseof using an impulse sealer. In this case, end portions of both thelaminate films 1, 2 are arranged ahead an impulse sealer 7 at a givenopposed posture as shown in FIG. 2( a) or at a mitre posture in theillustrated embodiment and the laminate films 1, 2 are fused byinstantaneously heating through an action of the impulse sealer 7 byapplication of impact current, and a pushing plate 8 is forwarded atsubstantially the same time as in the fusion as shown in FIG. 2( b) toforce flexible deformation of the films 1, 2 under the clamping of thefilms 1, 2 previously acted by a clamper 9, whereby both the films 1, 2are cut at an upper edge of the fused portion and also the thus cut edgeportion is separated away from the impulse sealer 7 to conduct coolingand curing to fusion-join the mutually opposite oriented base filmlayers 3, 4.

Moreover, numeral 10 is a pusher pushing the two laminate films 1, 2toward the front face thereof prior to the operation of the impulsesealer 7.

The thus formed mitre-shaped fusion joint portion 11 of the orientedbase film layers 3, 4 has a sufficiently large joining strength ascompared with tension acting to the laminate film 1, 2 in the packagingapparatus, and can pass between longitudinal seal knifes in a continuousfilling and packaging apparatus for a material to be packed as it is,and also liquid tightness, airtightness and heat sealing strengthrequired in a packaging bag can be developed by such a passing.

As shown in FIG. 3( a), it is preferable that the fusion joining portion11 is extended so as to somewhat incline with respect to a widthwisedirection Y-Y of the laminate film 1, 2. In such a joint portion 11, themutually coupled laminate films 1, 2 are applied to the packagingapparatus and folded into two in the widthwise direction as shown inFIG. 3( b), and at such a state longitudinal heat seal portion 12 isformed at both free end portions and lateral heat seal portion 13 isformed at intervals in a longitudinal direction of the film to conductthe filling and packaging of the material to be packed, wherein theextending position of the joint portion 11 can be shifted between frontface portion 14 a and rear face portion of a packaging bag 14 to beproduced to an extending direction of the longitudinal heat seal portion12. As a result, stress concentration in a specified place of thepackaging bag 14 or the like can effectively be prevented to enhance thetear strength of the packaging bag 14.

Usually, the packaging bag 14 having the joint portion 11 is disposedafter the production of the packaging bag 14 from a viewpoint of theappearance, so that it is not required to have a higher strength equalto the packaging bag as a product, and is sufficient to have a strengthcapable of preventing leakage, scattering and the like of the materialpacked in the bag without causing the breakage of the bag until thecompletion of the filling and packaging.

FIG. 4 is an enlarged section view illustrating another embodiment, inwhich the joint portion 11 between the oriented base film layers 3, 4 asmentioned in FIG. 1 is folded toward the side of the laminate film 1 andthe sealant layer 5 of the film 1 is opposed to the sealant layer of thefusion joint portion 11 and then these sealant layers are fusion-joinedby, for example, heat sealing.

According to such a coupling structure between the laminate films 1, 2,the joining strength at the coupled portion of the films can be furtherenhanced, and also the more excellent liquid tightness and airtightnesscan be provided.

Even in this case, the fusion joint portion 11 is preferable to beextended obliquely with respect to the widthwise direction of thelaminate film 1, 2. Thus, when the longitudinal sealing is applied toboth free end portions of the laminate film, as shown by a phantom linein FIG. 4, the joint portion is not existent in a free end portion of,for example, the laminate film 1 joined to the joint portion 11 and alsounevenness is not existent in the heat sealed surface, so that thereliability of the longitudinal heat seal is enhanced and furtherexcellent airtightness or the like is ensured and hence a higher heatsealing strength can be realized.

When the laminate film 1, 2 is provided with a middle layer not cuttingby the impulse sealer 7 such as aluminum foil, paper or the like, asshown in FIG. 5, it is preferable to arrange a shearing means comprisinga shear knife 15 horizontally forward-moving from one base portion tothe other base portion adjacent to a lower side of the impulse sealer 7and the pusher 10, and a receiving depression 17 formed in the otherbase portion and defining a receiving knife 16 contributing to shearingof an end portion of the film in collaboration with the shearing knife15. In this case, even if the impulse sealer 7 as a cutting sealer ischanged into the other fusion sealer in addition to the use of theimpulse sealer, after the mutual mitre-shaped joining of the orientedbase film layers 3, 4, end portions of the films continued thereto canbe surely cut at a given position. For instance, the folded fusion ofthe joint portion 11 between the oriented base film layers 3, 4 as shownin FIG. 4 can be always conducted at a constant fusion joining form.

Incidentally, the laminate films having the following laminationconstruction are fusion-joined by using the impulse sealer or the likeand adopting two coupling methods shown in FIG. 6 (a: mitre joining, b:mitre folded joining), and the tensile strength of the coupled portionis measured to obtain the following results.

Construction of Laminate Film

-   {circle around (1)} NY¹⁵/XA-S⁵⁰-   {circle around (2)} PET¹²/D/aluminum deposited PET¹²/XA-S⁴⁰-   {circle around (3)} NY¹⁵/D/Al⁷/XA-S⁵⁰    wherein    -   NY¹⁵: biaxially oriented nylon film layer (15 μm)    -   XA-S⁵⁰: polyethylene layer based on a metallosene catalyst        system (50 μm)    -   PET¹²: biaxially oriented polyethylene terephthalate film layer        (12 μm)    -   D: adhesion layer through dry lamination    -   XA-S⁴⁰: polyethylene layer based on a metallosene catalyst        system (40 μm)    -   Al⁷: aluminum foil (7 μm)        Joining Method

a: mitre joining: As shown in FIG. 6( a), the oriented base film layersare hot-cut and sealed in form of a mitre under pressure.

b: mitre folded joining: As shown in FIG. 6( b), the oriented base filmlayers are hot-cut and sealed in form of a mitre under pressure, andthen the mitre sealed portion is folded and the sealant layers areheat-sealed under pressure.

Report of Test Results

At first, the joining methods a and b are carried out by using thelaminate film {circle around (1)}. A relationship between the joiningmethod and tensile strength is shown in Table 1. As seen from theresults of Table 1, the strength is higher in the joining method a thanthe joining method b.

TABLE 1 Joining Value of tensile method strength [N/15 mm width] a 5.19b 34.50

Then, tensile strengths of the laminate films {circle around(1)}-{circle around (3)} and tensile strengths of joint portions by thejoining methods a, b are shown in Table 2.

TABLE 2 Tensile strength [N/15 mm width] Film Joining Joining Laminatefilm *1 method a method b {circle around (1)} NY¹⁵/XA-S⁵⁰ 64.48 5.1934.50 {circle around (2)} PET¹⁰/D/aluminum 76.54 5.10 45.18 depositedPET¹²/XA-S⁴⁰ {circle around (3)} NY¹⁵/D/Al⁷/XA-S⁵⁰ 63.80 11.27 43.90 *1:Tensile strength of the laminate film itself cut into a strip of 15 mmin width

In the above laminate film construction, all of them show that the valueof the tensile strength in the joint portion is larger in the joiningmethod b than in the joining method b.

FIG. 7 is a sectional perspective view illustrating an embodiment of theapparatus according to the invention suitable for carrying out thefolded joining as mentioned above, in which numerals 21, 22 are a basepair.

The bases 21, 22 are the same plane in their upper faces and extend inparallel to each other at an interval δ permitting insertion of, forexample, front end portion 1 a and rear end portion 2 a of therespective laminate films 1, 2.

At the one base 21 in the mutually opposite portions of the bases 21, 22are arranged pushers 23, 24 pushing end portions 1 a, 2 a of the filmstoward the other base 22 at intervals in up-down directions oversubstantially a full length so as to forward, for example, in adirection substantially perpendicular to the opposite base face, andelastic tubes 25, 26 pushing these pushers 23, 24 in forward directionare arranged at rear face sides. Each of the elastic tubes 25, 26 shownat a shrunk state are arranged in a base depression specifying anexpansion form, and the pushers 23, 24 each made of an elastic material,a metallic material or the like are pushed onto the opposite base faceside by a required force through the expansion based on the supply ofpressurized fluid into the elastic tube 25, 26. Moreover, when thepusher 23, 24, is integrally united with the elastic tube 25, 26 byjoining or the like, the pusher 23, 24 can be moved backward accompaniedwith the shrinkage deformation of the elastic tube 25, 26.

Also, the pushers 23, 24 are possible to be one-piece body forwardmoving with one elastic tube.

In the other base 22 are arranged two upper and lower sealers 27, 28 atpositions corresponding to the respective pushers 23, 24. Each of thesesealers 27, 28 may be any one of a heat sealing system, an impulsesealing system, a high frequency welder sealing system, a supersonicsealing system and a laser system, but it is preferable that the sealer28 arranged at a lower side is a hot-cutting sealer and the sealer 27arranged at upper side is a fusion sealer. That is, when the orientedbase film layers 3, 4 of the laminate films 1, 2 are fusion-joined toeach other in a mitre form by the lower sealer 28, it is preferable thatan extra portion continued beneath the joint portion is removed byfusion in order to shorten the length of the joint portion in subsequentfolding.

In the illustrated embodiment, the upper and lower sealers 27, 28 areimpulse sealing systems, and the upper sealer 27 is, for example, aplate of 5 mm in width and the lower sealer 28 is, for example, a rod of1 mm in diameter, and these sealers 27, 28 are electrically insulated tothe base 22 through insulating bodies 29, 30.

Moreover, the lower sealer 28 as a hot-cutting sealer can directlycontact with the film end portions 1 a, 2 a by arranging so as toprotrude from an insulating body 30 as shown in FIG. 8( a). Also, asshown in FIG. 8( b), it is arranged so as to somewhat backward from thesurface of the insulating body 30, whereby the film end portions 1 a, 2a can be hot-cut and sealed through a radiant heat from the sealer 28.In the latter case, there is no fusion of the hot-cut film portion tothe sealer 28, so that beautiful hot-cutting can be always and surely beconducted.

In this case, the hot-cut sealing is carried out under a sufficientpushing of the pusher 24 onto the film end portions 1 a, 2 a and theheating, hot-cut sealing and cooling are conducted by the impulsesealing method for a short time, so that the heat shrinkage of thethermoplastic oriented base film layers can be sufficiently preventedand also the oriented base film layers can be sufficiently fused tostrongly adhere to each other.

In the apparatus having the above structure, it is preferable to arrangepositioning means of the laminate films 1, 2 magnets 31, 32 in theillustrated embodiment on the upper faces of the bases 21, 22. Moreover,when the magnets 31, 32 are arranged so as to embed in the bases 21, 22,it is required to use a steel rod or other sandwiching member for fixingthe respective laminate film 1, 2 in sandwich form, but when the baseitself is made of steel or the like, the magnet can be used as asandwiching member.

In any case, it is effective to arrange a measuring means for measuringa length of the end portion 1 a, 2 a, of the laminate film 1, 2 or thelike on the base 21, 22 in order to match with a printed pattern or thelike.

When the front end portion 1 a and rear end portion 2 a of the laminatefilms 1, 2 each comprising a thermoplastic oriented base film layer suchas biaxially oriented nylon film layer, biaxially orientedethylene-vinyl alcohol copolymer film layer or the like and a sealantlayer such as various polyethylene layer, ethylene-vinyl acetatecopolymer layer, non-oriented polypropylene, ethylene-acrylic acidcopolymer layer, ionomer layer or the like are coupled to each other byusing the apparatus having the above structure, given lengths of therespective end portions 1 a, 2 a are inserted between both the bases ata posture that the oriented base film layers are opposed to each otherunder the positioning action of the magnets 31, 32 as shown in FIG. 9(a), and both the film end portions 1 a, 2 a are pushed onto the sealer28 by the lower pusher 24 as shown in FIG. 9( b), and the mutualoriented base film layers 3, 4 are fusion-joined in a mitre form underan action of the sealer 28 to provide a hot-cut seal as shown in FIG. 9(c).

Then, the pusher 24 is moved backward as shown in FIG. 9( c) or it isnot moved backward, and the film rear end portion 2 a is pulled up fromboth the bases 21, 22, preferably until it is restrained by thepositioning gauge 33 inserted between both the end portions 1 a, 2 a,whereby the fusion joint portion 11 between the oriented base filmlayers 3, 4 is precisely positioned in correspondence to the upperfusion sealer 27.

In this case, the fusion joint portion 11 is necessarily delayed byfriction with the base 22 accompanied with such pulling-up to renderinto a posture of folding to the front end portion 1 a of the film 1.

Thereafter, the upper pusher 23 is moved forward under the taking-out ofthe positioning gauge 33 as shown in FIG. 10( b) to sufficiently adherethe sealant layer in the fusion joint portion 11 to the sealant layer ofthe film front end portion 1 a, while both the sealant layers aresufficiently fused under the action of the fusion sealer 27 to conductof both the laminate films 1, 2 as it is expected. Finally, both endportions 1 a, 2 a are taken out between the bases 1, 2 to complete aseries of the coupling operations as shown in FIG. 10( c).

FIG. 11 shows an enlarged section of the thus formed film coupledportion, in which numerals 3, 4 are oriented base film layers andnumerals 5, 6 sealant layers.

The coupled portion between the mutual laminate films can indicate ahigh joining strength in addition the excellent airtightness and liquidtightness.

Furthermore, the coupled portion contributes to the formation of thepackaging bag under an action of the sealant layer exposed to the otherside of the fusion joint portion 11 likewise the other portions of thelaminate films 1, 2 and can sufficiently realize a tensile strengthrequired for the packaging bag.

Therefore, when the laminate films having the coupled portion areapplied to, for example, an automatic filling and packaging apparatus tomanufacture a packaging bag while folding into two in the widthwisedirection and heat-fusing sealant layers at both free end portionsthrough the longitudinal heat sealing knife and continuously ordiscontinuously filling a material to be packed into the film, it isquite useless to temporarily stop the packaging apparatus even if thefilm coupled portion arrives at either longitudinal or lateral heatsealing knife.

Incidentally, when the oriented base film layer is a biaxially orientednylon film layer having a thickness of 15 μm and the sealant layer is apolyethylene layer having a thickness of 50 μm, the tensile strength ofthe coupled portion is about 35 N per width of 15 mm, which a about ahalf of the tensile strength of 70 N generally required for thepackaging bag, but is a sufficient tensile strength as a film connectingstrength in the filling (an optimum film tension in the filling is about500 mN per 15 mm width).

Also, the section of the coupled portion is shown in FIG. 12 asenlargedly viewed by a microscope at 100 magnification. Further, thebiaxially oriented nylon film layer face and polyethylene layer face inthe coupled portion are shown in FIG. 13( a) and FIG. 13( b), andparticularly it is confirmed that trace of the coupling is made small toa negligible extent in the side of the sealant layer.

Now, the extending direction of the above coupled portion is not limitedto the widthwise direction of the laminate film 1, 2 but may be extendedobliquely with respect to the widthwise direction. In the latter case,as mentioned, for example, in relation to FIG. 3, when the coupledlaminate films are folded into two in the widthwise direction and theoverlapped free end portion is subjected to the longitudinal heatsealing and the material to be packed is filled and packaged whilesubjecting to the lateral heat sealing at intervals in the longitudinaldirection of the film, the extending position of the coupled portion canbe shifted in the extending direction of the longitudinal heat sealedportion between the front face portion and the rear face portion in thepackaging bag, so that stress concentration or the like can beadvantageously prevented to more enhance the strength of the packagingbag as compared with the case that the coupled portion is overlappedlypositioned between both the portions, and also the peeling componentforce of the coupled portion can be advantageously reduced against theaction of tensile force in the extending direction of the film.

In the laminate film according to the invention, not only various filmlayers but also aluminum foil, paper, various vapor deposited layers,vinylidene chloride copolymer coat layer or other coating layer may beinterposed between the oriented base film layer and the sealant layer.

Moreover, if the laminate film 1, 2 is provided with a cut-impossiblemiddle layer such as aluminum foil, paper or the like, it is preferableto arrange a cutting means adjacent to a lower side of the pusher 23, 24and the sealer 27, 28, for example, a shearing means comprising ashearing knife 34 moving forward from the one base 22 to the other base21 and a receiving depression 36 formed in the other base 21 anddefining a receiving knife 35 contributable to shearing of the film endportion 1 a, 2 a as shown by a phantom line in FIG. 8( a). According tothis means, after the mitre-shaped mutual joining of the oriented basefilm layers, the film end portion followed thereto is surely cut at agiven position irrespectively of the hot-cutting sealer or the fusionsealer as the lower sealer 28, and thereafter the folding fusion of themutual joint portion of the base film layers can be always carried outunder a constant fusion form.

FIG. 14 is a schematic section view illustrating another embodiment ofthe pusher mechanism, in which one pusher 38 is arranged to be common toupper and lower sealers 27, 28 disposed on the insulating body 37. Forexample, in order to conduct the forward and backward movement of thepusher 38 over about 1500 mm in a direction perpendicular to a face ofthe figure, plural cylinders 39 are connected to the pusher 38 insteadof the elastic tube.

When the size enlargement over full length of the elastic tube issynchronized in a required accuracy, the elastic tube can be naturallyadopted even if the length of the pusher 38 is made long.

Even in such an apparatus, the coupled portion as is expected can beformed by alternately acting the sealers 27, 28 under the same steps aspreviously mentioned.

In any apparatuses, it is preferable to connect a tension means forabsorbing liner expansion under the action of the sealers 27, 28 to atleast one end of the sealers.

Moreover, the fusion joint portion 11 may be folded toward the side ofthe laminate film 2 and fused thereto though it is not illustrated.

The above coupling structure can be applied to a case that side portionsof two laminate films are coupled to each other in addition to the casethat the front end portion of the one laminate film 1 is coupled to theread end portion of the other laminate film 2.

Although the invention is explained with respect to a case that laminatefilms are used in the automatic filling and packaging, it is of courseapplicable to various laminate films other than those for packaging inaddition to those for general packaging bag.

INDUSTRIAL APPLICABILITY

According to the invention, the mutual coupling of the laminate films iscarried out without using a connecting material such as an adhesive tapeor the like, whereby not only the excellent airtightness and liquidtightness but also the high coupling strength can be obtained, and thefilm coupled portion obtained by joining the oriented base film layersto each other can be passed through the packaging apparatus under steadyoperating state of the apparatus without temporarily stopping the mainfunctional part thereof and so on likewise the other portions of thelaminate films, so that the operation efficiency and the efficiency canbe largely improved as compared with the conventional technique that thetemporary stop and reoperation of the packaging apparatus are repeatedevery the arrival of the coupled portion at the heat sealing knife orthe like and also the yields of the laminate film and the material to bepacked can be largely improved.

1. A packaging bag comprising a coupling structure of laminate films,each laminate film comprising a thermoplastic oriented base film layerand a sealant layer that couple end portions of the laminate films toeach other, in which the oriented base film layers are fusion-joined toeach other in a mitre form and a protruding amount of the fusion jointportion from the laminate films is about 50-800 μm, the fusion-jointportion of the oriented base film layers extending along the laminatefilms with respect to an edge of one of the laminate films, wherein thefusion joint portion is configured such that, when viewed from alongitudinal cross-section, a free planar end of the fusion jointportion is inclined obliquely with respect to the width direction of thelaminate films.
 2. The packaging bag according to claim 1, wherein thefusion-joint portion of the oriented base film layers is folded toward aside of one of the laminate films to join mutually opposed sealantlayers with each other.
 3. The packaging bag according to claim 1,further comprising: a longitudinal heat sea portion along at least oneof the laminate films; and a lateral heat seal portion along at leastone of the laminate films.